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Dairy processing: Vitamin addition

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Introduction

The following provides recommended practices that dairy processors can use to ensure the accurate addition of vitamins to fluid, evaporated and dry milk products.

Definitions

For the purpose of this document, the following definitions apply:

Vitamin premix
A vitamin preparation supplied to a commercial processor, to be used in the fortification of fluid milk, milk powder and evaporated milk products as supplied or as a part of a vitamin solution. Vitamin premixes are available as liquid concentrates, powders or beads.
Vitamin solution
A blend of a vitamin premix and a suitable diluent.

Raw materials

Preparation of vitamin solutions

Vitamin addition

Vitamin addition can be accomplished at different points in the processing system through continuous flow or batch methods.

Continuous flow method - fluid products

Batch method – fluid products

Continuous flow method - dry powdered premix added to finished powder

Batch method - dry powdered premix added to finished powder

Finished product evaluation - quality control

In order to verify the quantity of vitamin(s) in the finished product, maintain records and perform laboratory analysis as outlined below.

Records

Analysis

Review

Calculations

The Food and Drug Regulations (FDR) outlines the vitamin fortification of dairy products based on the recommended daily intake (RDI) as per Schedule K.  Table 1 illustrates an example of the vitamin fortification levels based on 100 millilitres (mL) of fluid milk, reconstituted dry milk, or  reconstituted evaporated milk.

Table 1 – Illustrative example of the vitamin fortification levels (as applicable) per 100 mL of milk (fluid, reconstituted)
Vitamin FDR requirement Range based on RDI
(852 mL of milk / day)
A 1200 to 2500 International Units (IU)/RDI 140.8 to 293 IU/100 mL
D 300 to 400 IU/RDI
Coming into force:
2 micrograms (µg)/100 mL
35.2 to 46.9 IU/100 mL
Coming into force:
2 µg/100 mL
C 60 to 75 milligrams (mg)/RDI 14.08 to 17.6 mg/100 mL

Determining the volume of a vitamin premix prepared by weighing

Liquid premixes can be measured by weight instead of volume. Use the specific gravity (density) of the liquid premix to convert this weight to a volume.

Use the formula V = M / SG

where

V = amount of liquid vitamin premix used (mL)
M = weight of liquid premix used (g)
SG = specific gravity (density) of liquid premix (g/mL)

Example calculation

The specific gravity of a liquid vitamin premix is 1.045 g/mL. A weight of 3.5 g was used.

What is the volume of the liquid vitamin premix used?

V = M / SG
V = 3.5 g / 1.045 g/mL
V = 3.35 mL of liquid vitamin premix used

Determining the concentration of a diluted vitamin solution

If a liquid vitamin premix is further diluted prior to use, determine the concentration of the diluted vitamin solution prior to calculating either the theoretical value or the calculated value.

Use the formula  Cd = (Cp × Vp) / Vd

where

Cp = concentration of the vitamin premix (IU/mL)
Vp =  volume of the vitamin premix used  (mL)
Vd =  volume of the diluted vitamin solution to be prepared (mL)
Cd =  concentration of diluted vitamin solution (IU/mL)

Example calculation

The concentration of a vitamin D premix is 205,000 IU/mL. 24 mL of this premix is used in the preparation of 500 mL of diluted vitamin solution.

What is the concentration of the diluted vitamin solution?

Cd = (Cp × Vp) / Vd
Cd = (205,000 IU/mL × 24 mL) / 500 mL
Cd = 9840 IU/mL

This value (Cd) will be used for "C" when calculating the theoretical value or the calculated value in the next 2 sections.

Theoretical values

Theoretical value is used to determine how much vitamin premix should be added to achieve the desired vitamin concentration in the final product. The pasteurization method used (batch or continuous flow) will affect how this value is calculated, as will the use of a diluted vitamin premix.
Note: for the purpose of the calculations, the quantity of milk to be fortified must be converted to mL before entering it into the formula.

Batch method

V = TQ / C

where

V = volume of vitamin premix used (mL)
T = theoretical concentration of vitamin in the final product (IU/mL)
Q = quantity of milk to be fortified (mL)
C = concentration of vitamin premix (IU/mL)

Example calculation

If the desired theoretical concentration (T) in the final product is 38.15 IU/100 mL of Vitamin D (refer to Table 1), calculate the volume of vitamin premix (V) required in order to achieve this desired fortification level.

First, convert the theoretical concentration of vitamin to IU/mL:

38.15 IU/100 mL / 100 mL = 0.3815 IU/mL

V = volume of vitamin premix used (mL)
T = 0.3815 IU/mL of Vitamin D
Q = 1800 L (1800 L × 1000 ml/L = 1,800,000 mL)
C = 205,000 IU/mL of Vitamin D

V = TQ / C
V = [0.3815 IU/mL x 1,800,000 mL] / 205,000 IU/mL
V = 686,700 IU / 205,000 IU/mL
V = 3.349 mL

Therefore, the volume of vitamin premix needed to achieve a level of 38.15 IU/100 mL of Vitamin D in the final product is 3.35 mL. 

Continuous flow method

P = TF / C

where

P = vitamin pump speed (mL/minute)
T = theoretical concentration of vitamin in the final product (IU/mL)
F = flow rate of milk (mL/minute)
C = concentration of vitamin premix (or concentration of diluted vitamin solution) (IU/mL)

Example calculation

If the desired theoretical concentration (T) in the final product is 39.975 IU/100 mL of Vitamin D (refer to Table 1), calculate the vitamin pump speed (P) required in order to achieve this desired fortification level.

First, convert the theoretical concentration of vitamin to IU/mL:

39.975 IU/100 mL / 100 mL = 0.39975 IU/mL

P = vitamin pump speed (mL/minute)
T = 0.39975 IU/mL (39.975 IU/100 mL) of Vitamin D
F = 64 L/minute (64 L/minute × 1000 mL/L = 64,000 mL/minute)
C = 9840 IU/mL

P = TF / C
P = [0.39975 IU/mL x 64,000 mL/minute] / 9840 IU/mL
P = 25,584 IU/minute / 9840 IU/mL
P = 2.6 mL/minute

Therefore, the vitamin pump speed needed to achieve a level of 39.975 IU/100 mL of Vitamin D in the final product is 2.6 mL/minute.

For either the batch or continuous flow methods, multiple calculations can be completed to determine the theoretical concentration of the vitamin in the final product (T) based on different operating conditions. 

The theoretical value (T) used in setting up the operating conditions is compared to the calculated value (CV) to determine the correlation between the 2 values on a daily basis.

Calculated values

Calculated Value is used to estimate the actual vitamin concentration in the milk. The use of diluted vitamin premix will affect the calculation of this value, refer to the section Determining the concentration of a diluted vitamin solution . The calculated value should fall within the ranges indicated in Table 1.

CV = CU / Q

where,

CV = calculated level of vitamins in final product (IU/mL)
C = vitamin premix concentration (or concentration of diluted vitamin solution) (IU/mL)
U = total volume of vitamin premix used (or volume of diluted vitamin solution) (mL)
Q = total quantity of fortified finished product (mL)

Example calculation

CV = calculated level of vitamins in final product
C = 50,000 IU/mL of Vitamin A
U = 64.8 mL
Q = 1810 L (1810 L × 1000 mL/L = 1,810,000 mL)
CV = CU / Q
CV = [50,000 IU/mL × 64.8 mL] / 1,810,000 mL
CV = 3,240,000 IU / 1,810,000 mL
CV = 1.79 IU/mL of Vitamin A

This needs to be converted to IU/100 mL

Therefore: 1.79 IU/mL × 100 mL = 179 IU/100 mL

CV = 179 IU/100 mL of Vitamin A

Converting International Units (IU) of Vitamin D to micrograms (µg)

The Vitamin D level can be expressed in either IU or µg. Since 40 IU of Vitamin D is equal to 1 microgram (µg) of Vitamin D, convert from one to the other using either multiplication or division.

Example calculations

To convert IU to µg, divide the number of IU by 40.

For example, 300 IU of Vitamin D is equivalent to 7.5 µg:

300 IU / 40 IU/µg = 7.5 µg

To convert µg to IU, multiply the number of µg by 40.

For example, 2 µg of Vitamin D is equivalent to 80 IU:

2 µg x 40 IU/µg = 80 IU

To convert IU/100 mL to µg/100 mL, divide the number of IU/100 mL by 40.

For example, 30 IU/100 mL is equivalent to 0.75 µg/100 mL:

30 IU/100 mL / 40 IU/µg = 0.75 µg/100 mL

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